A thorough understanding of the friction and wear processes which occur in a total joint replacement prosthesis is essential to both the improvement of existing designs and the development of new ones. The express objective of this proposal is a comprehensive investigation of friction and wear phenomena of total joint replacement materials using a 12 channel wear screening machine. A standard wear test procedure for comparative evaluation of candidate materials will be established and repeatability and reliability of the test machine will be proven. Some new materials now in various stages of clinical trial have not had adequate laboratory testing, including Titanium 6Al 4Vn alloy and moulded UHMWPE. Both of these materials will be extensively tested in our wear program. The effects of metallic surface finish on wear performance will be investigated. The test conditions under which polymer transfer films are formed will be carefully studied and a comparison of specimen counterfaces with the surfaces from removed clinical implants will yield further understanding of the in vivo mechanism of wear. The effects of long-term implantation in animals on the wear of polymer specimens will be examined. The test methods of our program will provide a quick, reliable experimental method for obtaining meaningful data on the friction and wear properties of large numbers of test specimens from a variety of materials.